Code P0300, multiple random misfire

1997 MITSUBISHI MONTERO
185,000 MILES • 3.5L • V6 • 4WD • AUTOMATIC
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IKE H
  • MEMBER
  • 3 POSTS
Dtc P0300 changed plugs and wires swapped ICM with known good, one swapped coils with known good ones, and still have the same problem. no change in engine performance. Problem getting worse affecting drivability.
Jun 30, 2022 at 9:07 PM
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STRAILER
  • ✓Experienced Mechanic
  • 55,500 POSTS
This can be because you have a weak fuel pump, clogged fuel filter or a bad MAF/MAP sensor. Neither the MAF nor MAP sensor will show up in a code you just need to try them. Here is a guide to help you check the fuel pump pressure and the location of the fuel filter, MAP and MAF sensors. Check out the diagrams (below). Let us know what happens and please upload pictures or videos of the problem.
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Jul 1, 2022 at 11:37 AM
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IKE H
  • MEMBER
  • 3 POSTS
I changed the fuel filter it has been about 7 years. Then i went to check the map sensor i figured if i had it running and unplugged it i would notice a difference in engine performance. There was no difference in performance when i unplugged it. Is that a good sign that it's bad?
Jul 2, 2022 at 7:34 AM
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STRAILER
  • ✓Experienced Mechanic
  • 55,500 POSTS
Yep, if no change it doesn't sound like it is providing any feed back data to the computer.
Jul 3, 2022 at 3:36 AM
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